I can tell you because I have been in all four major bombers from WWII: B-17, B-24, B-25, and B-29.
The B-17 and B-25: tight and very tight.
The B-24 and B-29: relatively spacious, compared to the 17 and 25.
However, all of them were designed for 19-year old kids with zero body fat. The B-29 has a 40-foot long tunnel that goes from the forward pressurized section to the aft pressurized section. Part of crew training is to crawl through the tunnel.
Thanks for the comparison. Guess I won’t be touring any B-25s. There’s actually one available for rides right next to my house at the Arlington Fly-In this weekend.
Forgot about the B-29 tunnel. Built a model as a kid that showed this feature. I guess claustrophobics need not apply. Or, just be the pilot. I doubt their duties required crawling through very often.
I also heard that P-47s had the most spacious fighter cockpit of the era. Some wag said you could warm yourself up by running around the seat.